IPO lock-in periods

A lock-in period is a fixed time after a company lists on the stock exchange during which named shareholders cannot sell, pledge freely or transfer their shares. The shares are held in a frozen state in the depository, the system that keeps shares in electronic form, until the date passes.

The rule exists to protect people who buy in the IPO. If founders and early investors could sell the day the stock lists, the market would be flooded with shares and public buyers would be left holding the price risk. A lock-in forces insiders to stay invested while the new shareholders settle in. It also tells the market that the people who know the company best are not rushing for the exit.

The rules sit in the SEBI (Issue of Capital and Disclosure Requirements) Regulations, 2018, usually called the ICDR rules. SEBI is the Securities and Exchange Board of India, the stock market regulator. As of October 2026, the broad pattern for a mainboard IPO is as follows, but the exact dates for any one company are printed in its offer document, so always read that.

A practical point for anyone reading IPO news: lock-in dates are counted from the date of allotment, not the date of listing, and listing usually follows allotment by a few days. So the day a lock-in ends may fall a little earlier than a simple count from the listing date suggests. Companies and exchanges publish the exact dates, and brokerage research notes often keep a calendar of them. If you hold shares of a newly listed company, it helps to know who the large locked-in holders are and when each block is released, since this tells you how much stock could reach the market and when.

• Promoters, minimum contribution: the promoters must hold at least 20% of the post-issue capital, and that slice is generally locked in for 18 months from allotment.
• Promoters, anything above that 20%: generally locked in for 6 months.
• Capital-expenditure-heavy issues: where the money raised is mainly for projects and meets the prescribed test, the promoter periods can instead be three years and one year.
• Other pre-IPO shareholders (venture funds, angels, employees with shares): generally 6 months from allotment, with some exceptions, such as certain employee-benefit shares and eligible institutional investors.
• Anchor investors: half of their allotment is locked in for 30 days and the other half for 90 days from allotment.

Companies listing on the SME platforms of NSE and BSE face a stricter regime, because these companies are smaller and riskier. Reported figures for SME issues are longer: the promoters' minimum contribution is locked in for three years, any extra promoter holding is released in stages over one to two years, and other pre-IPO shareholders are generally locked in for a year.

Do not mix the two sets of numbers. A mainboard investor reading about a six-month lock-in should not assume the same applies to an SME listing. Check the offer document of the specific issue.

On the expiry date, the locked shares become free to trade. It does not mean holders will sell, but the market knows they can. Traders often watch these dates because a large block becoming tradable raises the possible supply of shares. When a start-up's early investors hold a big stake, the expiry of their six-month lock-in is closely watched.

Price moves around expiries are not guaranteed, and many expiries pass quietly. The effect depends on how much is unlocked compared with the shares already trading freely (the free float), how the stock has performed since listing, and whether investors want to sell at the current price. A fund that bought at a low price years ago may sell part to return money to its own investors. A founder may sell nothing at all.

For founders, the lock-in means that listing is not a cash-out day. Most of their wealth stays tied up in the company's shares for at least a year and a half under the usual mainboard pattern. They can still earn a salary and may be able to sell small amounts through an offer for sale at the time of the IPO, but the bulk of their stake stays put.

For early investors, the lock-in decides when they can return money to their own backers. Venture funds have a fixed life, so a fund close to the end of its term may plan its exit around the day its lock-in ends. This is one reason investors negotiate carefully about listing timing in the term sheet.

The red herring prospectus (RHP) and the final prospectus list the shares subject to lock-in and for how long. After listing, the company files a shareholding pattern with the exchanges each quarter, and the exchanges publish notices about shares coming out of lock-in. Reading these is more reliable than relying on news summaries or social media posts.

Our guides on the DRHP and the price band explain where these documents sit in the IPO process. Rules in this area are amended from time to time, so check the current ICDR text on SEBI's website or with a qualified professional before making a decision. This guide is general information and not investment, legal or tax advice.